pcs120 f2014 final exam with answers to post

PCS120 Fall 2014 Final Examination DATE: December 11, 2014

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RYERSON UNIVERSITY

DEPARTMENT OF PHYSICS

FACULTY OF SCIENCE

FINAL EXAMINATION

DURATION: 150 minutes

Student number Section Print First Name Print Last Name

(Last five digits)

Your Instructor (Check): Dr. T. Antimirova Dr. Karshafian

INSTRUCTIONS:

DO NOT OPEN THE TEST UNTIL YOU ARE TOLD TO DO SO.

●This is a closed book multiple-choice evaluation. Only pens, pencils, erasers, calculators and your

Ryerson ID are allowed on your desk.

●A formula sheet is attached. No other aids are permitted.

●Your Ryerson photo ID must be on your desk at all times.

●Pagers and cell phones must be silenced and placed in the bags at the front of the room. Earphones

are not allowed.

●Talking to another student or glancing over another student’s paper is not permitted and it may

result in a charge of academic misconduct.

●Please WRITE your solution in the space provided, select the option that is closest to the correct

answer and circle it in the exam booklet, then CAREFULLY transcribe your answer onto the

bubble sheet.

●All questions are of equal weight. Incorrect answers will receive a mark of zero.

●Normally, only the bubble sheets will be marked, but we reserve the right to do a check of the

solutions. Whenever the nature of the question requires a written solution, the correct answer without

the supporting solution may not be credited.

● Do not fold your bubble sheet.

●The formula sheet may be detached. The remaining exam pages must not be unstapled.

●The exam consists of 28 questions on pages 2-15. Once you are allowed to open the

examination paper, verify that you have all the pages. Inform one of the invigilators if any

pages are missing.

●At the end of the test, insert your bubble sheet into the examination booklet and hand

in both.

Please sign here indicating you have read and understood the above instructions.

SIGNATURE:______________________________________________

DO NOT OPEN THE TEST UNTIL YOU ARE TOLD TO DO SO.

Note: Verify that you have all 15 pages (all questions) before you start writing the test.

First letter of your LAST name


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Questions

1) The motion of a particle is described in the velocity versus time graph shown in the figure. We

can say that its speed

A) increases.

B) decreases.

C) increases and then decreases.

D) decreases and then increases. correct

E) does not change

2) The figure shows the position of an object as a function of time during the time interval from time t

= 0.0 s to time t = 9.0 s. What is the displacement of the object?

A) 5.0 m

B) 1.0 m correct

C) 9.0 m

D) 3.0 m

E) 2.0 m


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3) A toy car moves across a horizontal floor with an acceleration of 0.100 m/s2 in a direction opposite

to its velocity. The car has a velocity of 4.00 m/s after moving a distance 6.00 m across the floor.

What was the initial speed of the car?

A) 4.15 m/s correct

B) 5.85 m/s

C) 4.60 m/s

D) 5.21 m/s

E) 3.85 m/s

4) A small ball is hit straight up (vertically) into the air from the ground with a speed of 30.0 m/s.

Determine the time at which the ball passes a point of 25.0 m above the ground for the first time.

A) 0.513 s

B) 0.995 s correct

C) 5.13

D) 0.27 s

E) 1.17 s


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5) A car accelerates while being towed to the right on a rough surface. Which is the correct free-

body diagram for this scenario?

Answer c

6) Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from

the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s.

Neither person experiences any significant air resistance. Just as they reach the surface of the lake

below

A) the speed of Alice is larger than that of Tom. correct

B) the speed of Alice is smaller than that of Tom.

C) they will both have the same speed.

D) the speed of Tom will always be 9.8 m/s larger than that of Alice.

E) the speed of Alice will always be 25 m/s larger than that of Tom.


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7) A small airplane is flying at a speed of 200 m/s in level flight (horizontally) at an altitude of 800

m. A package is to be dropped from the airplane to land on a target on the ground. Ignore air

resistance. At what horizontal distance away from the target should the package be released so that it

lands on the target?

A) 0 m

B) 2560 m correct

C) 3620 m

D) 800 m

E) 1230 m

8) A satellite orbits the earth a distance of 1.50 × 107 m above the planet's surface and takes 8.65

hours for each revolution about the earth. The earth's radius is 6.38 × 106 m. The acceleration of this

satellite is closest to

A) 0.0690 m/s2

B) 0.870 m/s2 correct

C) 1.91 m/s2

D) 2.72 m/s2

E) 9.80 m/s2


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9) A box is being pulled to the right by a rope that angles upward. Which statement about the

magnitudes of the forces is true in this situation?

A) Norman force is larger than weight of the box

B) Norman force is equal to the weight of the box

C) Normal force is smaller than the weight of the box correct

D) Normal force is smaller than the kinetic friction

E) Normal force is equal to the kinetic friction

10) The force of air drag acting on an object depends on the speed of the object and its direction is

opposite to the object's velocity. For the object that is thrown vertically upward in the presence of a

drag force, which statement about the acceleration is true?

A) The magnitude of its acceleration is greatest right after the object is released. Correct

B) The magnitude of its acceleration is greatest the top of its trajectory.

C) The magnitude of the acceleration of the object is the same throughout the entire trajectory.

D) The magnitude of the acceleration in equal to g.

E) The acceleration is zero.


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11) A 50.0-kg box rests on a horizontal surface. The coefficient of static friction between the box and

the surface is 0.300 and the coefficient of kinetic friction is 0.200. What is the friction force on the

box if the box is being pushed by a force of 175N applied horizontally?

A) 140 N

B) 98.0 N correct

C) 0 N

D) 490 N

E) 175 N

12) A 50.0-kg block is being pulled up a 16.0° slope by a force of 250 N which is parallel to the

slope. The coefficient of kinetic friction between the block and the slope is 0.200. What is the

magnitude of the acceleration of the block?

A) 0.528 m/s2

B) 0.158 m/s2

C) 0.412 m/s2 correct

D) 0.983 m/s2

E) 0.260 m/s2


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13) An object on a rope is lowered at a steadily decreasing speed. Which statement is true?

A) The rope tension is greater than the object’s weight. correct

B) The rope tension equals the object’s weight.

C) The rope tension is less than the object’s weight.

D) The rope tension can’t be compared to the object’s weight

E) The rope tension is zero

14) A traffic light weighing 100 N is supported by two ropes as shown in the figure. The tensions in

the ropes are closest to:

A) 50 N

B) 56 N

C) 63 N

D) 66 N

E) 83 N correct

Answer: E

Var: 1


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15) On a horizontal frictionless floor, a worker of weight of 900 N pushes horizontally with a force of

200 N on a box weighing 1800N. As a result of this push, which statement could be true?

A) The worker will accelerate at 1.08 m/s2 and the box will accelerate at 2.17 m/s2, but in opposite

directions.

B) The worker will accelerate at 2.17 m/s2 and the box will accelerate at 1.08 m/s2, but in opposite

directions. Correct

C) The worker and box will both have an acceleration of 2.17 m/s2, but in opposite directions.

D) The box will not move because the push is less than its weight.

E) The worker and box will both have an acceleration of 1.08 m/s2, but in opposite directions

16) The figure shows two 1.0 kg-blocks connected by a rope. A second rope hangs beneath the lower

block. Both ropes have a mass of 0.25kg. The entire assembly is accelerated upward at 2.3 m/s2 by

force F. What is the magnitude of the tension at the top end of rope 1?

A) 15N

B) 2.9 N

C) 3.5 N

D) 18 N correct

E) 9 N


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17) A car drives over a hilltop that has a radius of curvature 0.120 km at the top of the hill. At what

speed would the car be traveling when its tires just barely lose contact with the road when the car is at

the top of the hill?

A) 41.8 m/s

B) 45.5 m/s

C) 34.3.m/s correct

D) 27.6 m/s

E) 22.2 m/s

18) A 600-kg car is going around a banked curve with a radius of 110 m at a speed of 24.5 m/s.

What is the appropriate banking angle so that the car stays on its path without the assistance of

friction?

A) 29.1° correct

B) 13.5°

C) 33.8°

D) 56.2°

E) 60.9°


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19) A small glider is coasting horizontally when suddenly a very heavy piece of cargo falls out of the

bottom of the plane. You can neglect air resistance. Just after the cargo has fallen out

A) the plane speeds up and the cargo slows down.

B) the plane speeds up but the cargo does not change speed.

C) neither the cargo nor the plane change speed. correct

D) the cargo slows down but the plane does not change speed.

E) both the cargo and the plane speed up.

20) During a collision with a wall, the velocity of a 0.200-kg ball changes from 20.0 m/s toward the

wall to 12.0 m/s away from the wall. If the time the ball was in contact with the wall was 60.0 ms,

what was the magnitude of the average force applied to the ball? 1ms=10-3 s.

A) 40.0 N

B) 107 N correct

C) 16.7 N

D) 26.7 N

E) 13.3 N


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21) A traveler pulls on a suitcase strap at an angle 36° above the horizontal. If 439 J of work are

done by the strap while moving the suitcase a horizontal distance of 15 m, what is the tension in the

strap?

A) 36 N correct

B) 29 N

C) 41 N

D) 44 N

E) 56 N

22) Swimmers at a water park have a choice of two frictionless water slides as shown in the figure.

Although both slides drop over the same height, h, slide 1 is straight while slide 2 is curved, dropping

quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the end of slide 1

compares with v2, the speed of a swimmer reaching the end of slide 2?

A) v1 > v2

B) v1 < v2

C) v1 = v2 correct

D) No simple relationship exists between v1 and v2 because we do not know the curvature of slide 2.

E) It is impossible to answer without knowing masses of both swimmers.


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23) In the figure, determine the character of the collision. The masses of the blocks, and the

velocities before and after are given. The collision is

A) perfectly elastic correct

B) partially inelastic

C) completely inelastic

D) characterized by an increase in kinetic energy

E) not possible because momentum is not conserved

24) A girl throws a stone from a bridge. Consider the following ways she might throw the stone. The

speed of the stone as it leaves her hand is the same in each case, and air resistance is negligible.

Case A: Thrown straight up.

Case B: Thrown straight down.

Case C: Thrown out at an angle of 45° above horizontal.

Case D: Thrown straight out horizontally.

In which case will the speed of the stone be greatest when it hits the water below?

A) Case A

B) Case B

C) Case C

D) Case D

E) The speed will be the same in all cases. correct


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25) A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m tall

building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the

building. What is the minimum amount of work that the worker did in lifting the bucket?

A) 3920 J

B) 400 J

C) 560 J

D) 4080 J correct

E) 160 J

26) From what height above the surface of the earth should an object be dropped to initially

experience an acceleration of 0.9200g? The radius of the earth is 6.38 × 106 m.

A) 272 km correct

B) 260 km

C) 554 km

D) 510 km

E) 1200 km


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27) Two identical small charged spheres are a certain distance apart, and each one initially

experiences an electrostatic force of magnitude F due to the other. With time, charge gradually leaks

off from both spheres. When each of the spheres has lost half its initial charge, the magnitude of the

electrostatic force will be

A) 1/16 F

B) 1/8 F

C) 1/4 F correct

D) 1/2 F

E) F

28) A proton is placed in an electric field of intensity 700 N/C. What are the magnitude and direction

of the acceleration of this proton due to this field? (mproton = 1.67 × 10-27 kg, e = 1.60 × 10-19 C)

A) 6.71 × 109 m/s2 opposite to the electric field

B) 6.71 × 1010 m/s2 opposite to the electric field

C) 6.71 × 1010 m/s2 in the direction of the electric field correct

D) 67.1 × 1010 m/s2 opposite to the electric field

E) 67.1 × 1010 m/s2 in the direction of the electric field

THE END

pcs120 f2014 final exam with answers to post

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